Use OSM as the single source of mountain passes

Replace the centcols CSV download/enrichment pipeline with OSM PBF
extraction as the primary (only) source: merge osmpass into mountain_pass,
drop the centcols table and model fields, filter to named passes with
elevation, and remove the centcols CLI flags.

1 files changed, 98 insertions, 0 deletions

diff --git a/mountain_pass/extract.go b/mountain_pass/extract.go
new file mode 100644
index 0000000..81bed68
--- /dev/null
+++ b/mountain_pass/extract.go
@@ -0,0 +1,98 @@
+package mountain_pass
+
+import (
+	"context"
+	"database/sql"
+	"fmt"
+	"io"
+	"log/slog"
+	"os"
+	"strconv"
+	"strings"
+
+	"github.com/paulmach/osm"
+	"github.com/paulmach/osm/osmpbf"
+)
+
+const insertStatement = `
+	INSERT INTO mountain_passes (osm_id, name, elevation, latitude, longitude)
+	VALUES (?, ?, ?, ?, ?)
+	ON CONFLICT(osm_id) DO UPDATE SET
+		name = excluded.name,
+		elevation = excluded.elevation,
+		latitude = excluded.latitude,
+		longitude = excluded.longitude
+`
+
+func ExtractMountainPasses(ctx context.Context, pbfPath string, db *sql.DB) (int, error) {
+	file, err := os.Open(pbfPath)
+	if err != nil {
+		return 0, fmt.Errorf("failed to open pbf file: %w", err)
+	}
+	defer file.Close()
+
+	scanner := osmpbf.New(ctx, file, 4)
+	scanner.SkipWays = true
+	scanner.SkipRelations = true
+	scanner.FilterNode = isMountainPass
+
+	tx, err := db.BeginTx(ctx, nil)
+	if err != nil {
+		return 0, fmt.Errorf("failed to begin transaction: %w", err)
+	}
+	defer tx.Rollback()
+
+	stmt, err := tx.PrepareContext(ctx, insertStatement)
+	if err != nil {
+		return 0, fmt.Errorf("failed to prepare insert: %w", err)
+	}
+	defer stmt.Close()
+
+	count := 0
+	for scanner.Scan() {
+		node, ok := scanner.Object().(*osm.Node)
+		if !ok {
+			continue
+		}
+		elevation, hasElevation := parseElevation(node.Tags.Find("ele"))
+		var elevationValue any
+		if hasElevation {
+			elevationValue = elevation
+		}
+		if _, err := stmt.ExecContext(ctx, node.ID, node.Tags.Find("name"), elevationValue, node.Lat, node.Lon); err != nil {
+			return count, fmt.Errorf("failed to insert osm pass %d: %w", node.ID, err)
+		}
+		count++
+	}
+	if err := scanner.Err(); err != nil && err != io.EOF {
+		return count, fmt.Errorf("failed to scan pbf: %w", err)
+	}
+	if err := tx.Commit(); err != nil {
+		return count, fmt.Errorf("failed to commit transaction: %w", err)
+	}
+	slog.Info("Extracted mountain passes", "count", count, "source", pbfPath)
+	return count, nil
+}
+
+func isMountainPass(node *osm.Node) bool {
+	if node.Tags.Find("mountain_pass") == "yes" {
+		return true
+	}
+	return node.Tags.Find("natural") == "mountain_pass"
+}
+
+func parseElevation(ele string) (int, bool) {
+	ele = strings.TrimSpace(ele)
+	if ele == "" {
+		return 0, false
+	}
+	for _, candidate := range strings.Fields(ele) {
+		if value, err := strconv.Atoi(candidate); err == nil {
+			return value, true
+		}
+		if value, err := strconv.ParseFloat(candidate, 64); err == nil {
+			return int(value), true
+		}
+	}
+	return 0, false
+}